Researchers have found geological evidence of the first Brexit. A new study published in the journal Nature Communications showed the destruction of a bridge that connected ancient Britain to Europe for 10 million years.
The bridge was about 20 miles wide that ran from Dover to Calais and protruded hundred of miles into Britain and France. The bridge was made of chalk, as it’s shown in the cross-section where it was ripped off at the white cliffs of Dover.
The researchers spent many years studying the event and were able to determine what happened to the bridge that once joined the island to the continent. They believe that a lake overflowed 450,000 years ago, which caused the damaging of the bridge, and then a next flood completely opened the Dover Strait.
“This was really one of the defining events for northwest Europe – and certainly the defining event in Britain’s history,” said lead author Professor Sanjeev Gupta from Imperial College in London, according to the BBC. “This chance geological event, if it hadn’t happened, would have meant Britain was always connected to the continent.”
Geological ‘Brexit’ started 450,000 years ago
The study explains that during the last ice age, the water was frozen in ice sheets during cold periods and then released to the oceans in warmer times, causing the sea levels to rise. At these times, Britain would be enclosed by water but the bridge, which stood between 100 to 300 feet above the waves, was never met by the water.
However, about 450,000 years ago things changed when a glacier that covered almost the entirety of Britain edged out across the North Sea and attached to a glacier covering Norway. The North Sea dammed and the rivers that drained into it, including the Thames and the Rhine, began to form a large lake.
As the level of the lake rose, the water started to fall from the Dover-Calais chalk bridge, causing the bridge’s erosion. The western side of the bridge retreated as the water eroded it and a section gave away. Then a flood took place near the bridge, and the lake poured itself into the English Channel.
The researchers estimate that the incident took place 430,000 years ago, judging by a layer of sediment that was found on the floor of the Atlantic Ocean. However, the bridge collapsed entirely 160,000 years ago.
A second lake was formed in the Northern Sea, and its southern boundary was a wall of sediment that remained after the flood of the first lake. It seems that a possible earthquake caused the remaining sediment wall to collapse, causing the lake to rush out and completely destroying the land bridge.
‘Brexit’ theory seems plausible to other geologists
The theory, although plausible, has not been proved. In 2007, Gupta and Jenny S. Collier of Imperial College London conducted tests on the underwater topography of the English Channel. The tests showed that west of the Strait of Dover, a group of deep valleys had been cut through the channel’s foundation.
The nature of the underwater walls and islands suggested that they had been shaped by a flood of the large force. The evidence led scientist to believe that a catastrophic collapse of the land bridge in Dover-Calais had unleashed a massive flood into the English Channel.
Years ago, a series of the major underwater holes were discovered in the Channel seabed, when researchers for the construction of the Channel Tunnel were conducted. Now, researchers found that the holes were most likely caused when the lake overspilled.
“These holes are now infilled with sediment, but what’s interesting is that they are not linear features like canyons or valleys -they are isolated depressions,” said Gupta. “So we interpret these as large plunge pools. We think there was lake water falling over this rock ridge in the Dover Strait through a whole series of waterfalls, which then eroded and carved out these depressions.”
Gupta explains that their research shows for the first time that a lake existed in the Dover Strait and that waterfalls were falling over the bridge. Gupta believes that the Lobourg Channel, east of the Dover Strait, may have been carved by the flood from the second lake.
Philip Gibbard, a geologist at the University of Cambridge, said that the reconstruction of the events was exciting and very plausible, according to The New York Times. Gupta stated that he hoped to add more detail to the study by drilling into the sediments that now fill the Fosses Dangeard, the name for the sediment-filled pits in the Channel’s bedrock. However, the Channel is the busiest shipping route in the world, and to study the Fosses, the team would need crossing two shipping lanes.
Gibbard says that although they discovered why Britain is no longer attached to Europe, it won’t always be the case. In the next ice age, the ocean waters will freeze into glaciers, and people will be able to walk from England to the continent, in Gibbard’s opinion.
Source: The New York Times